Alizarin Red S Staining Solution (2%, pH 4.2)

Guidelines (The following are our recommended procedures. This guideline is only a guide and should be modified according to your specific needs).
1. Alizarin Red S and Diphenyl Blue (HY-D0970) combined staining to detect corneal endothelial cell integrity^[1]
1.1 Corneal preparation: Place the separated corneal endothelium face up in a Teflon corneal cup.
1.2 Trypan blue staining: Add 0.25% trypan blue solution to cover the endothelium and stain at room temperature for 1.5 min; discard the staining solution, rinse briefly twice with physiological saline, and drain excess saline.
1.3 Alizarin Red S staining: Place the cornea back in the corneal cup, cover the endothelium with Alizarin Red S, and stain at room temperature for 1.5 min; discard the staining reagent and rinse twice with physiological saline.
1.4 Mounting and Observation: A 7.5 mm button-shaped tissue sample was excised from the center of the cornea using a surgical trephine, with the endothelium facing upwards. It was placed in saline solution, covered with a coverslip, and mounted on a grooved microscope slide. Observation and photography were performed under an optical microscope.
1.5 Result Interpretation: Trypan blue staining revealed deep blue cell nuclei (damaged/dead cells), while Alizarin Red S staining revealed orange-red cell boundaries (normal cell outlines). The area of ​​the red region was proportional to the number of normal endothelial cells.
2. Alizarin Red S Detection of Osteoblast Differentiation^[3]
2.1 Induction of Osteoblast Differentiation: MC3T3-E1 cells were seeded in well plates and cultured in α-MEM (without ascorbic acid) containing 10% fetal bovine serum. Osteoblast differentiation was induced using osteogenic medium (OSM) containing ascorbic acid (50 μg/mL) and β-glycerophospholipids (10 mM).
2.2 Staining: MC3T3-E1 cells were washed with 1×PBS, fixed with 70% ethanol at room temperature for 10 min, rinsed with distilled water, and stained with Alizarin Red S for 10 min to detect calcium deposition in the matrix.
2.3 Data Analysis: The area of ​​the red region was proportional to osteoblast differentiation.
3. Screening Test of Calcium Compounds in Synovial Fluid Using Alizarin Red S^[2]
3.1 Synovial Fluid Preparation: Aspirate synovial fluid into a disposable syringe, then transfer the fluid to a clean test tube containing heparin sodium anticoagulant.
3.2 Staining: Aspirate a drop of synovial fluid from the bottom of the test tube, place it on a clean slide, mix it with a drop of 2% Alizarin Red S, and cover with a coverslip.
3.3 Within three minutes of mixing, observe the mixture using a regular optical microscope and grade the intensity of the orange-red staining patches observed in each high-power field. The area of ​​the red region is proportional to the calcium compound content.
4. Detection of Calcium Deposition in WJ-MSCs Using Alizarin Red S^[5]
4.1 Cell Culture: WJ-MSCs were cultured in low-glucose DMEM supplemented with 10% fetal bovine serum (FBS) and 1% antibiotic-antimycotic solution. Cells were maintained in an incubator at 37°C with 5% CO₂, and the medium was changed every 2-3 days.
4.2 Cell Seeding: Cells were seeded into 6-well plates at a density of approximately 320,000 cells/well and cultured in basal medium (no osteogenic induction agents were added, and the medium was not changed throughout the experiment).
4.3 Fixation: Upon completion of the culture period, the medium was aspirated, and the cells were gently washed twice with pre-warmed PBS. Cells were fixed with 4% paraformaldehyde (PFA) in PBS for 15 minutes at room temperature. The PFA solution was then aspirated, and the cells were washed three times with PBS (5 minutes per wash) to remove residual fixative.
4.4 Staining: Following PBS washing, the fixed samples were rinsed with deionized water to remove phosphate ions that might interfere with staining, and then allowed to air-dry completely. 2% Alizarin Red S staining solution (pH 4.2) was added, and the samples were stained for 10 minutes at room temperature.
4.5 Washing and Drying: After staining, the samples were thoroughly rinsed with deionized water to remove unbound dye and allowed to air-dry completely prior to imaging and quantitative analysis.
4.6 Result Interpretation: Alizarin Red S chelates with calcium ions to form an orange-red complex; the area of ​​the stained region is directly proportional to the amount of calcium deposition.
MCE has not independently confirmed the accuracy of these methods. They are for reference only.

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.